Dumbbell



FIG. 1 is a perspective view of the dumbbell;

FIG. 2 is a front view of FIG. 1; and,

FIG. 3 is a left side view of FIG. 1.

The rear view, top view, and bottom view are identical to the front view, and therefore are omitted.

The right side view is identical to the left side view, and therefore is omitted. 

CLAIM The ornamental design for a dumbbell, as shown and described. 